Cam lapping machine



. 5, 1944. H. s. INDGE I CAM LAPPING MACHINE Filed June 7, 1943 ll Sheets-Sheet 1 ,WVb

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CAM LAPPING MACHINE Filed June '7, 1943 ll Sheets-Sheet 8 N G a \3 E HERBERT 5. INIJG'E.

Dec. 5, 1944. H. s. lNDGE 0AM LAPPING MACHINE Filed June '7, 1943 ll Sheets-Sheet 9 gnaw/toy HERBERT 5. INJJQE WWW-w M 8 Q mm mm QNN Dec. 5, 1944. H. s. INDGE CAM LAPPING MACHINE ll Sheets-Sheet 10 Filed June 7, 1943 Dec.- 5, H s [NDGE CAM LAPPING MACHINE Filed June 7, 1945 11 Sheets-Sheet ll mm t HERBERT 5. INDGE www.mn Mm,

Patented Dec. 5, 1944 2,364,2l&

CAMLABBING MACHINE Herbert. S. lndge vlfiestboro, Mass., assignor to. Nortonflomnany; Worcester, Mass, a corporaionofMa a hi s t Application Jnnea'l; 1943, Serial No. 489,907

12.01aims. This invention relates to abrading -machines,

and more particularly to a cam; lappingmachine.-

One object of the invention is to provide a simple and thoroughlypracticallapping-machine for simultaneously lapping a plurality of cams. A further object of the-invention; is to provide an automatic cam lapping; machine with aplurality oflappingarms eachofwhich is provided'witha continuous strip of=-a1orasive lapping; paper. A further object f the invention; is to provide a cam lapping machine with an automatic continuous abrasive paper-'feed'which: continuouslypresents. a freshahrading surface for the lapping; operation.

A further object of the invention is toprovide an automatic cam lapping machine; in which the work support for" the cams, to'be lapped" together; with the lapping arms are automatically and simultaneously reciprocated; Another object ot the inventionis to provide a lap ping machine in which the initial lapping operation,,is,hroduoed while the cams to be lapped are rotated fand the cams together, with the lappingarmsare simul+ taneously reciprocated; and the abrading lapping. paper isautomatically. and continuously fed, for, a predetermined time interval, A further object: of the invention is to providean automatic-mocha anism; for stoppingthe paperfeed and stopping the lapping arm reciprocation after. a., .predeter.-. mined lapping operation to facilitate a finish lapping operation.

Another. object of theiinvention is; to provide an automaticcam lapping Inachine-which-isar rangedto produce a. controlled lapping operation. for apredetermined period of timeduring -whiohintervalthe. abrasive paper is; automatically 1- and continuously. fed and thelapping arms and, the work i c om tic l ;rec p oc tedtfor-a predetermined. initial lapping operation after. which the lapping, operation 1 proceeds for a final. or finish lapping operation;- during which period: the lapping. arm reciprocation is stoppedg: and atheabrasive paper feeding ,mechanismqis; stopped for a p e e m n d; p riodmt. t mer A'i l r' henobject of the. invention: is to; provide; anralltomatic cam ap ing. machiaew ng which; anjelectricvtime delay, m-a r s o, ntro n: in a1 la ping Operation d nsw ch peration, er ams; to: be lapped arevrotategl andareoiprocated; the-laps. ping. armsare alsomeciprocated and ;the abrasive; lapping paper;- autoinatical1y; fed... the; electrical. e e a s er ce; t er-r s. m determinedutime. n alt o; tonr ez pping arm-1 reciprocatienst their asivepMI r s eedt nsh o set. n motion a e n i l ctric l-i ime; e a elax which.i cent.

trols the final or finish lappingoperatiomandi which serves after a predetermined timeintervah to move the lapping arms autoniaticall tot.an inoperative position to stop, theworlcdrive motor'to move the footstock. center. to-an-. inoperaztive position. Otherobj ects wi1li be in. part :.obvi:-. ous or in part pointed .outhereinafter;

The invention accordingly; consists: in the; fea;-. tures of construction, combinations .of' elements, and arrangements of parts; as? willibeexemplir. fied in the structure to be hereinafteridescrihed; and thescope of the. application Of'WhiChzWill be indicated in the followingclaims;

In the accompanying: drawings: in. which is shownone of variouspossiblev embodimentsof the mechanical features of I this invention,

' Fig. 1 is a front elevation of the improved cam lappingmachine;

Fig. 2 is aright handend elevatiom on a reducecl-scale of the machine-showninFig: 1;; v

Fig. 3 is a combined hydraulic-and electrical diagrammatic illustration. of the control-'mech anism of the improved cam lapping machine;

Fig. i is a longitudinallyvertical scctionalview,

. on an enlargedscale; taken through thehead stock spindle;

Fig. 5 is a" fragmentary elevation; .onan enlarged: scale, showing the chain drive for;- syn: chronously rotating the machine-.camshaft wit-h the Work spindle;

Fig; 6 is a fragmentarysectional'view through the idler sprocket taken approximately'on the line E--6 of Fig. 5;

Fig. 7 is asimilariragmentar-ysectional-view taken approximately on theline 1'-1=of== Fig; 5;

through the adjustably' supported idler' sprocketi Fig. 8 is a fragmentaryvertical sectional-view, on an enlarged scale, taken approximately-onthe line 88 of Figs. 15--and16, showing-the lapping armreciprocating mechanism;

Fig. 9 is a fragmentary sectional viewtakenapproximately on the'line 9 -9 =of Fig.- 22,"

Fig. 10 isa fragmentary sectional view-taken approximately on the line 1 l lls-Jil OffFig. .lfiz-showt ing. the frictional brakeron-the master cam. spin:

dle;

Fig. 11 is a fragmentary plan view, part-lyim section; taken approximately: on the'line 11+- I: of Fi 8, showing thelapping arm assemblyarockr shaft and the drive for reciprocating-the'lapping arms;

Fig. 12' is. a. fragmentary elevation. taken. approximately. on the line: I Z -l Lot-Fig: 11" showing the drive mechanism for; reciprocating the;1an-. pingrarms;

Fig. 13 is a fragmentary sectional view, on an enlarged scale, showing the spools for the abrasive lapping paper.

Fig. 14 is a fragmentary sectional view, on an enlarged scale, taken approximately n the line |4|4 of Fig. 21, showing the tensioning device for maintaining pressure between the abrasive lapping paper feed rolls;

Fig. 15 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line |5-|5 of Fig. 18, showing the arrangements of the lapping arms and the reciprocating mechanism together with the abrasive lapping paper feeding mechanism;

Fig. 16 is a fragmentary plan view partly in section taken approximately on the line |6|6 of Fig. 18, showing constructional details of the lapping arms and the master cam assembly for actuating the lapping arms;

Fig. 17 is a fragmentary plan view, on an enlarged scale, taken approximately on the line of Fig. 2 showing the lapping arm assembly;

Fig. 18 is a right hand end elevation, on an enlarged scale, of one of the lapping arms taken approximately on the line |8|8 of Fig. 1'7;

Fig. 19 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line |9| 9 of Fig. 17, showing the details of construction of the yieldable nose of one of the cam lapping arms;

Fig. 20 is a fragmentary horizontal sectional View taken approximately on the line 2020 of Fig. 18 showing the abrasive paper feed rolls;

Fig. 21 is a fragmentary plan view, on an enlarged scale, taken approximately on the line 2|2| of Fig. 22 showing the abrasive lapping rolls and the tensioning and feeding mechanism;

Fig. 22 is a fragmentary right hand elevation, on an enlarged scale, taken approximately on the line 22-22 of Fig. 20 showing the arrangement of the abrasive lapping paper feed rolls and the indexing mechanism;

Fig. 23 is a front elevation of a modified arrangement of the work supporting arbor as shown in Fig. 1;

Fig. 24 is a fragmentary sectional view, on an enlarged scale, taken approximately on the line 24-24 of Fig. 1 through the control lever and associated mechanism; and

Fig. 25 is a fragmentary sectional view through the actuating mechanism for the footstock center as shown in Fig. 3.

A lapping machine has been illustrated in the drawings in which a machine base 20 supports a longitudinally movable work supporting table 2 I. A rotatable work support is provided on the table 2| including a headstock 22 and a footstock 23. The headstock 22 supports a rotatable headstock spindle 24 in bearings 25 and 25. The headstock spindle 24 is provided with a driving mechanism such as for example an electric motor 21 having a built-in speed reduction gear unit. The electric motor 21 is provided with a multiple V-groove pulley 28 which is drivingly connected by multiple V-belts 29 with a multiple V-groove pulley 30. The pulley 30 is fixedly supported on a shaft 3| which is journaled in bearings (not shown) in the headstock 22. A worm 33 is keyed to the shaft 3| ,and meshes with a'worm gear 34 which is keyed to the headstock spindle 24.

The right hand end of the headstock spindle 24 is provided with a work engaging and driving member 35 which is arranged to support and drive the end of a work supporting arbor 36. The work supporting arbor 36 is arranged to support a plurality of aeroplane cams 31 and 38 to be lapped.

The footstock 23 is provided with a footstock center 40 which is rotatably supported within a slidably mounted sleeve 4| within the footstock 23. A hydraulically operated mechanism is provided for moving the footstock center-4D to and from an operative position to support the right hand end of the work supporting arbor 35. This mechanism may comprise a fluid pressure cylinder 42 which contains a slidably mounted piston 43. A piston rod 44 is connected at one end to the piston 43. The other end of piston rod 44 is pivotally connected to a link 45. The link 45 is in turn pivotally connected to a pivotally mounted bell crank lever 46. The other end of the bell crank lever 46 is connected by means of a stud 41 with a link 48. The link 48 is pivotally conected to a slidably mounted sleeve 49. A compression spring 50 is contained within the sleeve 49 and serves yieldably to maintain footstock center 40 in operative position when the bell crank lever 46 and the link 48 are swung to an operative position.

The work supporting table 2| is preferably arranged so that it may be reciprocated during a lapping operation to impart a reciprocatory movement to the cams being lapped. A connecting rod 53 is provided having one end pivotally supported on the stud 52. The other end of the connecting rod 53 is connected to a stud 54 which is integrally formed on one end of a rotatable stud 55, the stud 54 being eccentrically formed relative to the axis of rotation of the stud 55. The upper end of the stud 55 is provided with a spiral gear 56 which meshes with a spiral gear 51 mounted on the right hand end of a rotatable shaft 58. The shaft 58 serves as a support for a gear 59 which in turn meshes with a gear 60. The gear 60 is integral with the worm gear 34 which is keyed to the headstock spindle 24. It will be readily apparent from .the foregoing disclosure that rotation of the headstock spindle 24 will be imparted through the gear 50, the gear 59, the spiral gears 5|56 to rotate the stud 55 and that imparts a rotary motion to the eccentric stud 54 which in turn will serve to impart a reciprocatory motion to the work supporting table 2| through the connecting rod 53.

Lapping arm support It is desirable to provide a movable support for a plurality of lapping arms so that they may be simultaneously and quickly moved to and from an operative position. A pair of spaced arms 62 and 63 are mounted on a rock shaft 64 (Fig. 2) which is supported in bearings on the rear of the machine base 20. The arms 62 and 63 are provided with horizontally extending portions which are connected by two spaced parallel bars or slide rods 65 and 66 which serve as slide rods or ways for supporting a plurality of lapping arms to be hereinafter described.

The lapping arm assembly supported by the arms 62 and 63 is arranged so that it may be automatically moved to and from an operating position to facilitate loading of cams to be lapped into the machine and removing them therefrom after a lapping operation has been completed. In order to move the entire lapping arm assembly to and from an operative position, a fluid pressure mechanism is provided including a fluid pressure cylinder 68 which is pivotally connected by means of a stud 69 with the base 20 of the machine. A piston 10 is slidably mounted withaces-era in the cylinder 68and:is connect'ed atione end to arpiston rod 1I'. The'other end'of thepiston rod:

H is connected:by'a' stud- 12 with an. arm 13' pivotally mounted on' a: shaft14" Within the base 20 of the machine. The other end of thearm 13 is connected by a stud 15-to one end ofialink 16 connected by stud11with a togglelever 18. The adjacent ends of-thetoggle lever 18: and a toggle" 2; are in a position to holdthe arm 83*together with the arms '62 and 63- andthe entire lapping arm assembly in an operative position. When a lapping operation is started, fluid under pressure is admitted to the cylinder 69 to cause the piston 10 tomove downwardly (Fig. 3) and the piston rod 1Ito move toward the left(Fig. 2) to shift the levers 13, 16, 18; 19 and arm 83 into the broken line positions indicated in Fig. 2 to move the entire lappingarm assembly to an operativeposition.

A pair of slides 90 and 9I" are slidably supported onthe rods 65 and 66. Theslide 90 serves as a support for a plurality of lapping arms- 92", 9-3, 94, and 95. The slide 9| serves as a support for a plurality of lapping arms96, 91, 98 and 99. In addition to reciprocating the work supporting table 2! it is desirable to impart a reciprocatory movement to the lapping arms during a lappingoperation. In the preferred construction, a reciprocating mechanism is provided to simultaneously reciprocate the slide 90and 9! in the opposite direction so as to impart the secondary reciprocatory motion between the lapping element and the cam being lapped. A motor driven recip'roc'ating mechanism is provided comprising an adjustably mounted electric motor I which is supported on aplaten IOI' which is fixedly supported on the rock shaft 64 and is arranged to move with the arms 62 and 63 toward and from an operative position. The motor I00- is provided with a V-groove pulley I02 which is connected by a; V belt I03 with a pulley I04 which is mounted on one end of a rotatable shaft I05. The shaft I is rotatably supported. in single pillow block bearings I06 and I01 which are adjustably supported on the platen IN. The shaft I05 is provided with a multiple V-groove pulle I03 which is connected by multiple V-belts I09 with a multiple V-groove pulley IIO which is mounted on one end of a rotatable shaft III. The shaft III is provided with a pair of eccentrics H2 and H3 (Fig. 8) which are connected by connecting rods I I4 and H5 respectively; withstuds H6 and H1. The studs H6 and H1 are fixedly mounted on the slides 90 and 9|, respectively. It will be readily apparent from the foregoing 'disclosure-that when the motor I00 is set in motion, a simultaneous reciprocatorymovement will be imparted in opposite directions to the slides 90 and 9| to impart a reciprocatory movement to the lapping arms- I M aster cams In order to produce a controlled movement of the lapping arms; it is desirable to provide a the nose pieces to simultaneously lap a master 'cam' for" controlling the; transverse move:- ment ofceach: of thelapping arms. Amaster cam shaft I20 is. rotatably supported by bearings" I2.I and I22 which are in turnsupportedin fixed. relationship with the arms: 62 and 63 respectively,

The master cam' shaft I20 is preferably driven insychronism with the headstock spindle:24. The headstock spindle. 24. is provided with a keyed.

' sprocket I23 which is connected by a link roller chain I24iwith a sprocket. I25. The sprocket I25" is rotatably supported: on an extension of the trunnion shaft 64. An' adjustable: rotatably mounted idler sprocket I26 is provided to'facilit'ate tensioning: the roller chain I24. A sprocket I21 ismounted to rotate with. the sprocket I 25' and is connected by'means of a link chain I20 with a sprocket I29 which is mounted on the end of the master cam shaft I20. Anadjustably mounted idler sprocket- I30 is provided to facilitate tensioning of the driving chain I28. It will be apparent from the foregoing disclosure that rotation of the headstock spindle 24 willbe transmitted through the chain drive above described synchronously to rotate the master cam shaft I20; By driving from the headstock 22 to the trunnion shaft 64 and then from the trunnion shaft 64 to the master cam shaft I20, a synchronous drive of the work arbor 36 and the master" cam shaft I20 will be obtained in any position of the lapping arm assembly.

The master cam shaft I20 is provided with a plurality of master cams I32, I33, I34, I35, I36, I31, I38 and I39. These master cams are formedin pairs which are integral with each other as il-- lustrated in cross section in Fig. 16. The lapping arms 92, 93, 94, 95, 96, 91-, 98 and 99 are pro-- vided with adjustably mounted offset follower rollers I40, I'4I, I42, I43, I44, I45, I46 and I41, respectively, which serve to transmit the motion of the master cams to the lapping arms. The lapping arms are provided with an offset nose piece I48, I49, I50, I5I, I52, I53, I54, and I which are offset to facilitate a close relationship between pair of adjacent cams(Fig. 1'1).

The lapping arms 92, 93, 94, 95, 96, 91, 98 and 99 are arranged so that they may be moved transversely as controlled by the master cams above described. Tension'springs I56, I51, I58, I59, I60, I6I, I62, and I63 are provided to exert a forc on the transversely movable lapping arms to maintain the follower rollers in operative engagement with the master cams as the lapping operation proceeds and to impart a simultaneous controlled movement to the lapping arms (Fig. 16)

Each of the lapping arms 92, 93, 94-, 95, 90, 91, 98, and 99 is supported for a transverse movement by means of a plurality of-rollers I64, I65, I 60, I61, I68 and IE9 (Fig. 18). Each of the lapping arms is supported in an adjustable frame I10 (Fig. 18) which is provided with a dove-tailed surface I1I which mates'with the correspondingly shaped surface on the upper portion of the slides and BI respectively. 9 It will be readily apparent from this disclosure that the frames I10 carrying the lapping arms 92, 93, 94, 95, 96, 91, 98, and 99 may be readily adjusted relative to the slides 90 and 9| respectively, to position the lapping arms as desired.

Abrasive paper feed is provided for each of the lapping arms. The

rolls of abrasive paper are pivotally supported on a shaft I83 (Figs. 18) which is in turn supported by upwardly extending brackets I84 and I85 (Fig. 15), which are fixedly supported relative to the lapping arm assembly.

As shown in Fig. 18 a strip of abrasive paper I86 from the roll of paper I82 passes downwardly around the yieldable nose piece I55 on the lapping arm 99 and passes upwardly over a rod 206 and over a knurled feed roller I81 which is rotatably supported on a shaft I88 supported between the brackets I84 and I85 and passes downwardly between the periphery of the feed roller I81 and a feed roller I89 which is rotatably supported on a shaft I90. The shaft I90 is also supported by the brackets I84 and I85. A pair of gears I9I and I92 are fixedly mounted on the feed rollers I81 and I89 so that the two feed rollers I81 and I89 are rotated together to feed abrasive paper strip I86 therebetween. As illustrated in Fig. 21 the abrasive paper feed rollers are arranged in tegrally in pairs, 2. similar set of feed rollers I93 and I94 being formed integral with the feed rollers I81 and I89. A ratchet wheel I95 is fixedly mounted relative to the feed rollers I81 and I93. A holding pawl I96 is supported by the shaft I90 and serves to hold the ratchet wheel I95 against rotation in a counterclockwise direction (Fig. 22). An actuating pawl I91 engages the ratchet wheel I95 and is pivotally supported by a stud I98. The stud I98 is supported at one end of an arm I99 which is clamped onto the shaft I88. It will be readily apparent that an oscillating motion of the shaft I88 will be transmitted to turn the ratchet wheel I95 in a clockwise direction (Fig.

.22) to advance the abrasive paper I86 so as to present a fresh portion of abrading material across the nose I55 of the lapping arm 99.

A similar set of feed rollers 200 are provided for feeding abrasive paper from the abrasive paper rolls I and I16 to thealapping arms 92 and 93 respectively. A similar set of feed rollers I are provided for feeding abrasive paper from the abrasive paper rolls I11 and I18 to the lapping arms 94 and 95. A set of feed rollers 202 are provided to feed abrasive paper from the abrasive paper rolls I19 and I80 to the lapping arms 95 and 91 respectively. The feed rollers 200, 20I and 202 together with their actuating mechanisms re identical with that previously described (Figs. 21 and 22), consequently these mechanisms have not been illustrated and described in detail.

The feed rollers 200, 20I and 202 are opposed by feed rollers 203, 204, and 205 which are rotatably supported on the shaft I88.

In order to maintain a yieldable pressure between the feed rollers to index abrasive paper therebetween, the shaft I88 is preferably yieldably supported. A plurality of brackets 201, 208, 289, ZID and 2I I are fixedly clamped on the shaft I20. The other ends of the brackets 201, 208, 209, 2H) and 2H are fixedly clamped on'the rod 206. The opposite ends of the shaft I88 are supported in bearings 2 I2 and 2I3 which are in turn slidably supported in the brackets I84 and I85 respectively and compression springs 2I4 and M5 are provided normally to urge the shaft I88 toward the shaft I90. Each of the brackets 201, 208, 208, 2H1 and 2 is provided with a slidably mounted bearing block 2I6 (Fig. 14)' which serves as an intermediate support for the shaft I88. Compression springs 2I1 are provided in each of the brackets 201, 208, 209, 2I0, and 2 to maintain a pressur urging the shaft I88 towards the 1| shaft I90 thus to maintain a yleldable pressure between the opposed abrasive paper feed rollers above described. The details of only one of the brackets 2I I are shown in Fig. 14. All of the other brackets 201, 208, 209 and 2H] are identical in construction and consequently have not been illustrated in detail. Each of the brackets is provided with a slidably mounted stud 2I9 one end of which engages the slidable bearing block 2I6 and the other end of which engages an eccentric 2I8. If it is desirable to release the tension between the feed rollers, the levers 220, 220a, 2201), 220a, and 220d may be rocked in a counterclockwise direction (Fig. 14) to shift the eccentric 2I8 so as to move the slidably mounted bearing blocks 2l6 and shaft I88 away from the shaft I90 and thus separate the sets of feed rollers.

Hydraulic Motor In order to automatically and simultaneously actuate the pawl and ratchet abrasive paper feeding mechanism above described, a mechanism is provided for oscillating the shaft I88 simultaneously to index all of the abrasive paper to provide a continuous feeding of the abrasive paper during the lapping operation. This mechanism may comprise a self-contained fluid motor 225 which has been illustrated in section in Fig. 3 but will not be described in detail since this motor is identical with that shown in the prior United States patent to Wallace H. Wood, 2,212,871, dated August 27, 1940, to which reference may be had for details of disclosure not contained herein. The fluid motor 225 includes a cylinder 226 having a slidable piston 221 which is provided with a piston rod 228. The piston rod 228 is connected to a downwardly projecting arm 229 the upper end of which is fixedly clamped to the shaft I88. The fluid motor 225 is provided with a combined pilot and reversing valve 230 which is arranged to continuously reciprocate the piston 221 when fluid under pressure is pased through a pipe 23I from a source to be hereinafter described. It will be readily apparent that a continuous reciprocation of the piston 221 will impart a continuous oscillation to the shaft I88 which in turn serves to actuate simultaneously a two part pawl I91 on each of the arms I99 of the sets of feed rollers, simultaneously to impart a continuous feeding movement to the flexi'ole abrasive lapping paper. In case it is desired to stop the automatic feed of the abrasive paper on any one or more of the lapping arms, the feed pawls I91 (Fig. 22.) may be rocked in a clockwise direction to an inoperative position so that the oscillating motion of the shaft I88 will not impart a feeding movement to the abrasive paper passing between the adjacent feed rollers.

Hydraulic controls A hydraulically operated control mechanism is provided for controlling the various elements of the machine. A motor driven fluid pressure pump 235 is provided for drawing fluid through a pipe 236 from a reservoir 231 and passing fluid under pressure through a pipe 238 to a stop and start valve 239 (Fig. 3). A pressure relief valve 240 is provided to facilitate passing excess fluid under pressure from the system directly to the reservoir 231. The valve 240 is a standard variable pressure relief valve and consequently has not been illustrated in detail. The stop and start valve 239 is a piston type valve comprising a valve stem24l having a plurality of valve .aee ige-rs pistons formediintegrally therewith. In theposition'z'o'f the valve 239 (Fig. '3) fluid-under pressure passing through the pipe 238 passes outwardly through' a'pipe 242 into an end chamber 243 ine piston type controlvalve 244. The piston type controhvalve 244 comprises the valve .stem 245 having a plurality of valve pistons formed integrallytherewith. A chamber 246 of thevalve 2 44 is connected by apipe 241 with the stop-and start valve 239 and as shown in Fig. 3 is connected so as to exhaust fluid from the chamberz246 through a passage 248 and a pipe 249 into 'the reservoir 231. It will bereadily apparent from the foregoing disclosure that the start and stop valve 239 serves to control theadmission of fluid to and from the end chambers 2243:and 245 of the control valve 244 to shift the valve stem 24.5 either toward the right (Fig. 3)

into the position illustrated in the drawings at.

the end ofthe lapping cycle or to shift the valve stemi2'45 toward the left (Fig. 3) to initiate a lapping cycle. -'An adjustable valve 250 is provided in the pipe line 249 to facilitate controlling :the exhaustioifluidfrom the end chambers 243 rand246 of the control :valve 244' so asto control therate of movement of the valve stem 245 when it ismoved in either direction.

.The;cont'rol valvei'244 isoperatively connected .to controlitheadmission of fluid under pressure to the cylinder 68 to cause a movement of the .lappingarm assembly to and from an operative position, and totthe cylinder 42 to actuate the footstock center 46.

The control valve 244 is provided with valve chambers 255, 256 and .251. The valvechamber 2551's connected by apipe 258 with a chamber 1:259 formedin the upper end of the cylinder 68.

The chamber 256 of .the valve 244 is connected :byapipe ZBOWitlr-acchamber 26l stormed at the lower end of IthecylindBrBS. A combined check and throttle valve 262 is provided in the pipe line '266-which is arranged to allow substantially unrestricted passage of fluid through the pipe 2:66 when .fluidunderpressure is admitted to the cylinder chamber 26! to cause the lapping arm :assembly'to move to an inoperative position, but .is arrangedso .thata desired controlled rate of movement maybeobtained whenthe lapping arm assemblyis Inoved'to an operating position.

:Sinnlarlyathe'valve chamber 255 is connected @by apipe .263 with a cylinder :chamber 264 in .tliecylinder 4.2. .Theivalve chamber 256is connected bylalpipew2fi5 with a chamber 266 formed in the cylinder. 11; will be readily apparent from the foregoing dis-closure that the control valve :244 serves to control the admission to or :exhaustuof .fiuid .from the I'oppositeends of the cylinder 4.2,to actuate the foodstock center 46. The valve-chamber253 of the control valve 2'44 is connected by-ajpipe 268 to the pipe 238-which is .directlyconnected withthe pump 235 so that fluid underpressure is continually admitted to the valve chamber 256. The pipe 268 is also connected with a pipe 269 which is in turn connected with the pipe =23I to supply fluid under pressure .for actuatingthe fluid motor .225. A normally closed valve 219 is provided between the p pe .23l and .269 which serves as a stop and .start valveuto-stop'the fluidmotor 225 automatically, as Willbe; hereinafter described, during the lappingcycle. .Anielectric pull type solenoid 21l 1s. provided which .is'arranged when energized to 'open the va1ve 219 and'thus tostart'the fluid .motor..-2'25. Fluid -is exhausted'from the com- .bined ;;pilot and-reversing :valve 239 of :the fluid motor- 225 through a pipe i 212 :and' through an adjustable throttle valve 2.13 by means I of which speed of movement of the fluid motor 225 may be regulated. Fluid 'exhausts from the control waive 244 through a passage 214 and passes throughzan exhaust pipe 215'into the reservoir '231. Thepipe 212 which exhausts'fluid from-the fiuid moto'r 225 is connected to the 'exhaust'pipe Aninterlock mechanism is provided which cooperateswith the movement of the control valve 244110 prevent the movement of the lapping arm assembly into an operative position before the rootstock center 40 is moved into .operative engagement to position a workpiece to be lapped. This mechanism comprises a'flange 219 which is "fixedly imounted adjacent to the rear end of the 'valve s'tem'245. A spring presseddetentlZBllnormallyilies in the path of'the'fiange 219. The

'detent "280 "is connected by means of a flexible cable 28I with the'bell crankj'lever 46. "When fluid under pressure is passed into the cylinder chamber 264 to'rock the bell crank lever 46 in a clockwise direction to=move the footstock center 40 into an operative position, this' motion moves the cable 28i to withdraw the detent;280

out of the path of the 'fiange 219. It will be readily 'apparent from the foregoing disclosure 'that unless "the footstock center 49 has moved into an operative position, the valve stem r245, cannot-be shifted'towardthe left a sufficient distance to admit the fluid'under pressure through thepipe258 to cause a downwardmovement of the'piston 10 to-move thelapping arm assembly into an operative'position.

A similar spring-pressed detent: 282 is provided which lies'in the path of the flange :219- duringa lapping operation. The detent2'82 .is connected =toapivotally mounted bell crank lever 283 the upper end of which is connected by 'a flexible cable 284 '(Fig. 2) with the arm 63. The detent 282 serves to prevent ea movement of -the flange 219 and valve stem 245 toward 'therightito .pre-

vent withdrawal 'of'the footstock center 46 beiore thelapping arm assembly has been moved to an inoperative position.

A manua1ly operable control'lever 285 is flxedly mounted on the :outer endof a rock "shaft 286. A downwardly extending arm v.281, mounted on the inner end of the .rockshaft?286,..is connected by astud 2B8'to the upperrend of 'a link .289. "The lower end of the link 289*is connected 'bys a stud 290 to the'valve stem 24!. When it'is desired to shift the start'and stop valve 239 to initiate a lapping cycle, the control lever .285 is shifted in a counterclockwise direction into'the broken line position 285a (Fig. 3),'which movement is transmitted'through the rock shaft 286,

thearm 281 and the link 289 to cause a down- Ward movement of the valve stem 24| which shifts the valve pistons of the valve 239 downwardly so that .fluid under pressure is passed from 'the pressure line 238, through the pipe 241,

into the end chamberi246 of the control valve 244 ture 294 and link 293 to move toward the left (Fig.3) into the position illustrated. This movement shifts the arm '29l and the control lever 285 in 'a clockwise direction, from-position 285a into full line position 285, to stop the cycle at the end of the lapping operation. The solenoid 295 is energized automatically, as will be hereinafter described, to terminate the lapping operation after a predetermined time interval has elapsed.

The arm 29I is provided with an integral downwardly extending projection 296 which is arranged to engage and move an actuating plunger 291 of a normally open limit switch 298 so as to close the limit switch when the control lever 285 is shifted in a counterclockwise direction into broken line position 285a for the start of a lapping cycle.

A normally closed limit switch 300 is provided with an actuating roller 30I which lies in the path of an arm 302 (Fig. 3). The arm 302 is fixedly mounted on the arm 62 of the lapping arm assembly. The arm 302 is arranged so that when the lapping arm assembly is in an inoperative position, the normally closed limit switch 300 is automatically opened so as to prevent starting of the headstock motor 21.

A magnetic starter switch 305 is provided to control the starting and stopping of the forward or normal lapping rotation of the headstock motor 21. A magnetic reverse switch 306 is op- .eratively connected through a motor brake switch 301 (Figs. 1 and 3) to reverse the flow of current to the headstock motor 21 and through the motor brake switch 301 rapidly to stop it after the desired time interval. A similar magnetic starter switch 308 is provided for controlling the forward or normal rotation of the lapping arm reciprocating motor I and a magnetic reverse switch 309 is provided to control the reversal of the current to the motor I00. A motor brake switch 3I0 is operatively connected with the motor I00 which serves rapidly to stop the rotation of the motor I00 when it is desired to stop the reciprocatory movement of the lapping arm assembly.

In order to automatically control the lapping cycle a pair of electrical time delay relays 3| I and 3I2 are provided. These relays are shown diagrammatically in Fig. 3 and may be any of the standard commercial instantaneous reset timers which are in common use in the machine tool field. As illustrated in Fig. 3, a relay known commercially as Microfiex instantaneous reset timer, manufactured by the Eagle Signal Corporation, may be employed.

The time relay 3 is so connected in the electrical system that when the control lever 285 is shifted in a counterclockwise direction to start the lapping cycle, the valve stem MI is moved down so as to admit fluid under pressure to the pipe 241 to cause the valve stem 245 to move toward the left (Fig. 3) at the same time the normally open switch 298 is closed.'- During the initial shifting movement of the valve stem 245, fluid is admitted through the pipe 263 into the cylinder chamber 264 to actuate the footstock center to move it into operative engagement with the work supporting arbor 38, after which fluid is admitted to the cylinder chamber 259 of the cylinder 88 to cause a movement of the lapping arm assembly toward an operative position. During the movement of the lapping arm assembly, the arm 202 (Figs. 2 and 5) moves away from the roller SM and allows the normally closed switch 300 which is in series with the limit switch 298 to close. Closing of the limit switch 300 serves through the starter switch 305 to start the headstock motor 21 and at the same time sets the time relay 3II in motion to energize the starter switch 308 and starts the motor I00 to reciprocate v trated in Fig. 3.

the lapping arms and also energizes the solenoid 2H and opens the valve 210 to operate the fluid motor 225. When the fluid pressure pump 235 is started, the fluid is transmitted through the pipe 238, 268, 200 and 23I to actuate the fluid motor 225 when the solenoid 21I is energized by the time relay 3| I, to automatically operate the paper feeding mechanism continuously to feed abrasive paper. The individual paper indexing mechanisms are operative only when their actuating pawls are shifted to operative positions in engagement with the ratchet wheels previously described. The lapping operation proceeds for a predetermined time interval as governed by the time relay 3II during which time the headstock for the work drive motor 21 rotates the work supporting arbor 36, and at the same time reciprocates it in an axial direction. The rotary motion of the work drive motor is also transmitted through the link chain drive previously described synchronously to rotate the master camshaft I20 so as to impart a controlled motion to the lapping arms. After a predetermined time interval has elapsed, as governed by the time relay 3I I, the lapping arm reciprocating motor I00 is stopped and at the same time solenoid 21I is deenergized to allow the valve 210 to close, thus stopping the automatic continuous feeding of the abrasive lapping paper so that a final or finish lapping operation is obtained during which time the work rotates and reciprocates while the lapping paper is maintained stationary so as to produce a final lapping operation on the work piece. At the same time as the time relay 3II operates to stop the paper feed and the lap arm reciprocation, it operates to set in motion the second time relay 3I2 which is connected to govern the final or finish lapping operation. After a predetermined time interval as governed by the time relay 3I2, the solenoid 295 is energized to shift the control lever 285 from the broken line position 285a (Fig. 3) into the full line position 285 to shift the stop and start valve stem 24I into the extreme upper position, which movement in turn serves to shift the valve stem 245 of the control valve 244 toward the right into the position illus- When the control lever 285 is shifted to the full line position, the limit switch 290 is opened so that the headstock motor 21 will be stopped at the end of the lapping cycle. During this shifting movement fluid under pressure is admitted to the cylinder 88 to cause the lapping arm assembly to move to an inoperative position. Movement of the lapping arm assembly to an inoperative position serves to open the normally closed limit switch 300 which in turn serves to prevent starting the work drive motor 21 while the lapping arms are in an inoperative position. Shifting of the valve stem 245 then allows the hydraulic power to actuate the footstock 23 to remove the foodstock center 40 from operative supporting engagement with the Work supporting arbor 36.

A push button switch 3I4 is mounted on the front of the machine base 20 and is operatively connected to control the stopping and starting of the motor driven fluid pump 235.

The sets of earns 31 and 38 to be lapped are formed integrally in pairs on an annular shaped member such as used in the modern airplane motor. In order to support these rim-shaped cams, special clamping flanges 3I6 and 3" are mounted on the work supporting arbor 36 which serves to center and locate the product cams with respect to the work supporting arbor 36. A

regseazrs rdriving iplate 131:8 :having a centering .iDI'OjBCtiOIl iislprovidedLat rthe left-handgend of theaworlcsupporting. arbori36 to.loca-te:and drive theaarbor .in-

a predetermined .positionzwith respeetztotthe driving member 35 of thelheadstock spindle E24 and also to drive the arbor 36 touring "the lapping operation. Due .to theannula-r :ringeshaped oams .3! and .38lto1be1lapped, itismreferablerto laprtwo sets of 'cams at onetimeaasshown 'inrFig. .1 of

the drawings. During thisdapping. operation, the 4 operator may load a second :work supporting :arbor Bfiwwhich is provided'vvithlocating, supporting and clamping fianges 113m and i320 for supporting andflocating producticams similar to the clamping fianges 35 .6 and i3l'l. ilt should be "2 notedthation "the first lapping operation when the work supportingarbor 36 .is placed in operative position in :the machine. lapping "arms 92 and 93 are arranged toengage and lapthe cam 31, and the lapping arms 9B=and99ilare arranged to lap thelcam 38. On the next lapping operation using the'second work supporting arbor 36a. it should be noted th-at the flanges iil I 9 and'32ll are spaced closer together, so that on thesecon'cl lapping operation the'l-apping arms 94 and 95 Operation .The operation vof this improved lapping :machine will be readily apparentfrom thelforegoing disclosure. Two setsof work pieces to 'be lapped are clamped in position-on the worksupporting arbor "36 which ,isplaced :in a loading position on alpairrof spaced Work supporting arbor cradles .1312l rand'322 (Figs. "1 and 2) after which the work vanbor 3 iiis-rolled into position with the workarborifi in alignment withthe headstock work driving spindlefld :and the footstock center 4!]. The push button 3M is'then actuated to start the fluidipump 7. .35 and a knife switch 3l5 isclosed torender theelectricalcircuits of the machine readyfor alapp-ing operation. The main 'control"lever'285 is thenshifted manuallyin a counterclockwise direction (Figs. 1 and 3) to shift the stop and start valve 2'39 to a starting or down position "which admits fluid under [pressure through thepipe 241 to 'cause the control valve 244 to move toward theleft (Fig. 3) to initiate a lapping cycle. The "shifting movement oi the control valve Z'Mtoward the left serves first to admit fluid through the .pipe .263 to actuate the footstock center 40 so as to move it into operative supporting engagement with'the work arbor 3.6 after which fluid is admitted through the'pipe 258 tothe. cylinder .68 tomove the lapping arm assembly to an operativegposition. The movement .of thecontrol lever 285.120 a startingposition serves to .close .thenormally open limit switch 298 and the movement of the lapping arm assembly serves to close the normally closed limitswitch 1300 which closes a series circuit'to start the workdrive motor .21 and at the same time to setthe .time relayu3l'l in motion tostart the .motor we toimpart alreciprocatory movement to the pair of slides .SIlIand .9! which supportthelappingarms so as to impart a relative reciprocating movement to .thelapping .motion to th abrasivepaper: feedingrmechanism.

previouslydescribed. Thelappingoperationsproliceeds until .a predetermined time interval has elapsed. as governed by theitimerelay :3 If! iWhiCh "serves to "simultaneously top-the motor I110 thus stopping the xreciprocatlon of rthe T lapping arms, .at' thesame time thexsolenoid 121i is deenergized to close "the z-valveiflll to .stop'the :flui'd -motor 225 thereby stopping the automatic continuous zfeed'of the :abrasiveupaper, and at the same in- :stantthatime relay 312 is setzin'motion. to govtern the final -.or finish lapping'operation. After ca predetermined :"final or :finish ilapping operation is. produced, 'duringzwhich timerthe-abrasive lapping pap er is held: stationaryiand-ithe" lapping .arms-sare not reciprocated, :the time relay 312 ioperates :to energize?the solenoid'295 :to shift the aicontrol .lever 428511: in: a. clockwise direction 1 into ifullilinegposition (Fig. 53) "to initiate: a movement :of: the electrical and hydraulic controls toan inope ative 'position. .At thesame time, the stop and :start Va1Ve'f2'39 is moved upwardly 1 into the positionrshown in Fig. 53 which serves to admit fluid under pressure through the pipe 242 to the end chamber .24'3to move the valve stem 245 toward the .right into the position illustrated in Fig. .3 duringwhich time the lapping arm assem- FEM) :ibly .iS moved to ran inoperative position. Movei'ment'of thelapping arm assembly toan inoperative position serves to open the limit switch-3ll0, "aspreviously-described. The 'fluid under-pressure is "then admitted to the rootstock cylinder chamber 256 :to-withdraw the rootstock center 40. The work =arbor 36 may then be "removed :from'themachine and the'work arbor Met-placed in'position 'for the next lapping operation.

*It will b readily apparent-from the foregoing disclosure that'the preliminary or initial lapping I operation maybe automatically controlled by .the setting of the ttime relayj3ll and the duration of the final or finish'lapping operationmaybe readily controlled by manipulation of the time relay 3l2, thus.gproviding.anautomatic cycle of operation,. it.being onlynecessary for. the operator to initiatethe cyclehyshiftingthe maincontrol lever 1285 intotheposition 285a.

It, wi1l thus'beseen that therehas :beenrprovided by thi invention apparatus in x which the various objects .hereinabove set -forth atogether vwith many thoroughlygpractical advantages are successfully achieved. Asmanypossible embodimentsimaybe made ofthe above invention and .asmanychanges might'beamade in theembodiment above setyforth, .it is'to be understood that allmatter hereinsbeforeset forthor shown in the accompanying drawings is to i be interpreted as illustrative and not in a limiting sense.

I claim:

1. In a-cam lapping machine having a base. means including'arotatable*motor drivenhead- 'stoclcspindleto rotate a camshaftarotatable master cam, a synchronousdrive between said spindle and mastercam. a .slidably mounted lapping arm,. a follower on said arm which engages said master cam. means including 'a-motor to reciprocate said lapping arms during 4 .a lapping operation. and anlelectrical control system in- .cludingan electrical time "delay relay which is operatively'connectedzafter a predetermined-time interval "to stop said lapping arm "reciprocation andthereafter to StOJp' the 'rotation'of said headstock spindle after a lapping operation has been completed.

2. In a cam lapping machine having a base, means including a motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a slidably mounted lapping arm, a follower on said arm in operative engagement with said master cam, a continuous strip of abrasive lapping pauper on said arm, means automatically and continually to feed said lapping paper during a lapping operation, and an electrical control system including an electric time delay relay which is operatively connected after a predetermined time interval to stop said paper feed and thereafter to stop said headstock spindle after a predetermined lapping operation has been completed.

3. In a cam lapping machine having a base, a rotatablemotor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a slidably mounted lapping arm having a follower in operative engagement with said master cam, means including a motor to reciprocate said lapping arms, and an electrical control system including an electric time delay relay which is operatively connected after a predetermined time interval to stop said motor and lap arm reciprocation for a final lapping operation, and means thereafter to stop said headstock spindle after a predetermined final lapping operation has been completed.

4. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a continuous strip of abrasive lapping paper on said arm, means including a motor automatically and continuously to feed said lapping paper during a lapping operation, and an electrical control system including an electric time delay relay which is operative after a predetermined time interval to stop said motor and paper feed for a final lapping operation, and means thereafter to stop said headstock spindle after a predetermined lapp ng operation has been completed.

5. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam synchronously rotated with said spindle, a slidably mounted lapping arm having a follower in operative engagement with said master cam, means to reciprocate said lapping arm, a continuous strip of abrasive lapping paper on said arm. means automatically and continually to feed said lapping paper during a lapping operation, and an electrical control system including an electric time delay relay which is operatively connected after a predetermined time interval to stop said lapping arm reciprocation and said paper feed after a predetermined lapping operation to facilitate a final lapping operation.

6. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a slidably mounted lapping arm having a follower in operative engagement with said master cam, means including a motor to reciprocate said lapping arms, a continuous strip of abrasive lapping paper on said arms, means including a motor automatically and continually to feed said lapping paper during a lapping operation, and an electrical control system including an electric time delay relay which is operatively connected after a predetermined time interval to stop said motors so as to stop the lap arm reciprocation and to stop the abrasive paper feed after a predetermined initial lapping operation to facilitate a final lapping operation.

'7. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a lidably mounted lapping arm having a follower in operative engagement with said master cam. means including a motor to reciprocate said lapping arm, a continuous strip of abrasive laping paper on said arms, means including a motor actuated pawl and ratchet automatically and continuously to feed said lapping paper during a lapping operation, an electrical control system ncluding an electric time delay relay which is operatively connected after a predetermined time interval to stop said motors so as to stop the apping arm reciprocation and to stop the abrasive paper feed after a predetermined initial lapping operation to facilitate a final lapping operation, and a second electric time delay relay which is rendered operative by said first time relay after the initial lapping operation has been completed which is operatively connected after a predetermined final lapping operation to stop said headstock spindle.

8. In a cam lapping machine having a base, a rotatable camshaft support thereon to support a A plurality of cams to be lapped, means including a headstock spindle to rotate said cams, a rotatable master camshaft having a plurality of master cams thereon, a synchronous drive between said headstock spindle and said master camshaft, a plurality of slidable lapping arms, a follower on each of said lapping arms which is in operative engagement with one of said master cams, means including a motor to reciprocate said lapping arms in a direction parallel to the axis of said cams, a continuous strip of abrasive lapping paper on each of said lapping arms, a pawl and ratchet feed mechanism on each of said arms continuously to feed said abrasive paper during a lapping operation, means including a motor operatively connected simultaneously to actuate a plurality of said feeding mechanisms. and an electrical control system including an electric time delay relay which is operatively connected to stop said motors after a predetermined lapping operation so as to stop said lapping arm reciprocation and to stop said abrasive paper feed to facilitate a final lapping operation.

9. In a cam lapping machine having a base. a rotatable camshaft support thereon to support a plurality of cams to be lapped, means including a. headstock spindle to rotate said cams. a rotatable master camshaft having a plurality of master cams thereon, a synchronous drive between said headstock spindle and said master camshaft, a plurality of slidable lapping arms, a follower on each of said lapping arms which is in operative engagement with one of said master cams, means including a motor to rec procate said lapping arms in a direction parallel to the axis of said cams, a continuous str'p of abrasive lappin paper on each of said lapping arms. a pawl and ratchet feed mechanism on each of said arms continuously to feed said abrasive paper during a lapping operation, means including a motor operatively connected simultaneously to actuate a plurality of said feeding mechanisms, an electrical control system including an electric time delay relay which is operatively stop said headstock spindle.

10. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a

slidably mounted lapping arm having a follower in operative engagement with said master cam, means to move said lapping arm to and from. an operative position, means including a motor to reciprocate said lapping arm, a. continuous strip of abrasive lapping paper on said arms, means including a motor actuated pawl and ratchet automatically and continuously to feed said lapping paper during a lapping operation, an electrical control system including an electric time delay relay which is operatively connected after a predetermined time interval to stop saidmotors so as to stop the lapping arm reciprocation and to stop the abrasive paper feed after a predetermined initial lapping operation to facilitate a final lapping operation, and a second electric time delay relay which is rendered operative by said first time relay after the initial lapping operation has been completed which is operatively connected after a predetermined final lapping operation to stop said headstock spindle, and to move said lapping arm to an inoperative position.

11. In a cam lapping machine having a base, a rotatable motor driven headstock spindle to rotate a camshaft, a rotatable master cam which is synchronously rotated with said spindle, a slidably mounted lapping arm having a follower in operative engagement with said master cam, means including a fluid motor to move said lapping arm to and from an operative position, means including a motor to reciprocate said lapping arm, a continuous stripof abrasive lapping paper on said lapping arms, means including a motor actuated pawl and ratchet automatically and continuously to feed said lapping paper during a lapping operation, a solenoid valve to control said motor actuated pawl and ratchet, an electrical control system including an electrical time delay relay which is operatively connected after a predetermined time interval to stop said lap arm reciprocating motor and to actuate said solenoid valve so as to stop the lap arm reciprocation and to stop the abrasive paper feed after a predetermined initial lapping operation to facilitate a final lapping operation, and a second electric-time delay relay which is rendered operative by said first time relay after the initial lapping operation has been completed which is operatively connected after a predetermined final lapping operation to stop said headstock spindle and to move said lapping arm to an inoperative position.

12. In a cam lappin machine having a base, a rotatable camshaft supported thereon to support a plurality of cams to be lapped, means including a headstock spindle to rotate said cams. a rotatable master camshaft having a plurality of master cams thereon, a synchronous drive between said headstock spindle and said master camshaft, a movable lap arm assembly having a plurality of slidably mounted lapping arms thereon, a follower on each of said lapping arms which is in operative engagement with one of said master cams, means including a fluid motor to move said lap arm assembly to and from an operative position, means including a motor to reciprocate said lapping arms in a direction parallel to the axis of said cams, a continuous strip of abrasive lapping paper on each of said lapping arms, a pawl and ratchet feed mechanism associated with each of said arms continuously to feed said abrasive paper during a lapping operation, means including a motor operatively connected simultaneously to actuate a plurality of said feeding mechanisms, an electrical control system including an electrical time delay relay which is operatively connected to stop said lap arm reciprocating motor and to stop said, abrasive paper feed motor after a predetermined lappin operation so as to stop said lap arm reciprocation and to stop said abrasive paper feed to'facilitate a final lapping operation, and means including a second electrical time relay which is rendered operative by said first time relay after the initial lapping operation has been completed which is operative after a predetermined final lapping operation to stop said headstock spindle and to admit fluid under pressure to the lap arm assembly motor to move said assembly to an inoperative position.

HERBERT S. INDGE. 

